As we all know, Mac OS X has support for what is called 'fat binaries'. These are binaries that can carry code for for instance multiple architectures - in the case of the Mac, PowerPC and x86. Ryan Gordon was working on an implementation of fat binaries for Linux - but due to the conduct of the Linux maintainers, Gordon has halted the effort.

I can see a substantial benefit if we left the package manager behind... no longer would users be required to know whether they have an 386, 686, x86_64, ARM, or PPC installation: download and it'll work... at least, provided it was distributed as one. Right now, we have the package manager handling all of those distinctions; this would remove the vital dependencies on a specific package manager... at least, provided you have all the right versions of the libraries installed.

Not really. The package manager works the same way (and therefore has the same source code) for any installation or architecture.

Different distributions and/or different targetted architectures simply "point" the package managers at different URLs.

The end user doesn't have to know the right URL. The URLs for the package manager repositories are normally set up when the OS is installed on the machine in the first place. If an OS is installed and the machine runs at all, it will already be set correctly.

Packager managers/repositories work. They are far better than anything that is available for Mac or Windows. Why mess with them?